[clang] [llvm] [win][x64] Unwind v2 3/n: Add support for emitting unwind v2 information (equivalent to MSVC /d2epilogunwind) (PR #129142)

[Pedro Miguel Justo via cfe-commits]

pmsjt wrote:

> How do epilogs work in chained unwind tables? Do the epilog opcodes from the original table get ignored?

They are additive. When execution is on a fragment, it is assumed that all unwind opcodes from the parent fragment(s), all the way to the principal fragment, are already applied.

https://github.com/llvm/llvm-project/pull/129142